1. Field of the Invention
This invention relates generally to a photographic exposure control system with uniform trim control, and more particularly to a photographic exposure control system wherein the shutter blade elements are moved through a range of progressively varying aperture sizes at a determinate velocity and additionally including a trim control for uniformly varying exposure by changing the determinate velocity by which the shutter blade elements traverse the aperture range.
2. Description of the Prior Art
Fully automatic exposure control systems of the type used in Polaroid Corporation's SX-70 and Pronto type cameras are now well known in the art. Such fully automatic exposure control systems have generally employed a trim mechanism for providing the photographer with a degree of overriding personal control through which he may slightly vary film exposure to account for variations in the ambient scene lighting conditions as well as slight variations in the sensitometric characteristics of the film.
In photographic apparatus of the aforementioned type having light responsive exposure control systems, including scene light integrating circuits embodying photocells, the trim control has been arranged to selectively position a plurality of varying light transmissive sections over the light sensing photocell of the light responsive exposure control system. Such exposure control systems have also embodied follow focus arrangements as described in U.S. Pat No. 3,750,543, entitled "Focus Responsive Exposure Control System", by V. Eloranta et al. issued in common assignment herewith. Trim mechanisms of the aforementioned type have also been keyed to vary the follow focus control so that any exposure value alteration inserted as a trim from the trim control becomes simultaneously transmitted to the follow focus system as well as into the light detecting photocell. This arrangement has been utilized in systems of the so-called hybrid type as disclosed in U.S. Pat. No. 4,007,468, entitled "Trim Control Apparatus for Photographic Exposure Control System" issued Feb. 8, 1977 in common assignment herewith. Since trim mechanisms of the aforementioned type are operated in conjunction with follow focus systems, it has not been possible to provide an entirely uniform trim control across the entire range of apertures to which the shutter blade elements scan.
Therefore, it is a primary object of this invention to provide a uniform trim control for use with photographic apparatus of the type having automatic exposure control systems.
It is a further object of this invention to provide an exposure control system, wherein the shutter blade elements may be moved at a determinate speed through a progressively varying range of aperture sizes and wherein the exposure may be uniformly trimmed by varying the determinate speed at which the shutter blade elements traverse the aforementioned aperture range.
Other objects of the invention will, in part, be obvious and will, in part, appear hereinafter. The invention accordingly comprises the mechanism and system possessing the construction, combination of elements, and arrangement of parts which are exemplified in the following detailed disclosure.